Pattern antenna

Abstract

A pattern antenna, with desired antenna characteristics, that is formed in a small area is provided. The pattern antenna includes a substrate, a ground portion formed on a first surface of the substrate, an antenna element portion, a short-circuiting portion, and a connecting portion. The antenna element portion is a conductor pattern including a conductor pattern in which a plurality of bent portions are formed. The conductor pattern is formed on the first surface of the substrate and, and is electrically connected to the grand portion. The short-circuiting portion includes a conductor pattern formed in a second surface, which is a different surface from the first surface. The conductor pattern is formed so as to at least partially overlap with the conductor pattern of the antenna element portion as viewed in planar view. The connecting portion is configured to electrically connect the conductor pattern of the antenna element portion to the conductor pattern of the short-circuiting portion.

The invention claimed is: 
     
       1. A pattern antenna comprising:
 a substrate; 
 a ground portion formed on a first surface of the substrate; 
 an antenna element portion including a conductor pattern in which a plurality of bent portions are formed, the conductor pattern being formed on the first surface of the substrate and being electrically connected to the ground portion; 
 a short-circuiting portion including a conductor pattern formed in a second surface, which is a different surface from the first surface, the conductor pattern being formed so as to at least partially overlap with the conductor pattern of the antenna element portion as viewed in planar view; 
 a connecting portion configured to electrically connect the conductor pattern of the antenna element portion to the conductor pattern of the short-circuiting portion; and 
 a protruding portion electrically connected to the short-circuiting portion on the second surface of the substrate, the protruding portion including a conductor pattern formed so as to at least partially overlap with the conductor pattern of the antenna element portion that is disposed between the connecting portion and the ground portion as viewed in planar view. 
 
     
     
       2. The pattern antenna according to  claim 1 , wherein the antenna element portion includes the conductor pattern formed in a meander line shape. 
     
     
       3. The pattern antenna according to  claim 1 , wherein
 the short-circuiting portion and the protruding portion are each formed in a rectangular shape, and 
 the protruding portion is formed such that a distance from a center line in the longitudinal direction of the short-circuiting portion to the tip of the protruding portion as viewed in planar view is a length satisfying λ/4±0.3×(λ/4) where λ is a wavelength of an electromagnetic wave to be eliminated in the pattern antenna. 
 
     
     
       4. The pattern antenna according to  claim 1 , wherein
 the short-circuiting portion and the protruding portion are each formed in a rectangular shape, and 
 the protruding portion is formed such that a distance from a center line in the longitudinal direction of the short-circuiting portion to the tip of the protruding portion as viewed in planar view is a length L 1  satisfying λ0=λ/sqrt(∈r) and L 1 =λ0/4±0.3×(λ0/4) where λ is a wavelength of an electromagnetic wave to be eliminated in the pattern antenna, ∈r is a specific dielectric constant of the substrate, and sqrt(x) is a function that returns the square root of x. 
 
     
     
       5. The pattern antenna according to  claim 1 , wherein
 the short-circuiting portion and the protruding portion are each formed in a rectangular shape, and 
 the protruding portion is formed such that a distance from a center line in the longitudinal direction of the short-circuiting portion to the tip of the protruding portion as viewed in planar view is a length L 2  satisfying λ0=λ/sqrt(∈r) and L 2 =Kc×λ0/4±0.3×Kc×(λ0/4) where λ is a wavelength of an electromagnetic wave to be eliminated in the pattern antenna, ∈ r is a specific dielectric constant of the substrate, Kc (0≦Kc≦1) is a capacitance contribution rate caused by overlapping of the conductor pattern of the antenna element portion with the conductor pattern of the protruding portion as viewed in planar view, and sqrt(x) is a function that returns the square root of x. 
 
     
     
       6. The pattern antenna according to  claim 1 , wherein
 the protruding portion includes a plurality of portions formed on the second surface of the substrate, each of which does not overlap with the others.